ON THE COORDINATION SITES OF 2-AMINOCYCLOPENTENE-1-DITHIOCARBOXYLIC ACID TO NI(II), PD(II) AND PT(II) - A RESONANCE RAMAN INVESTIGATION

Resonance Raman spectroscopy has been used to clarify the controversia l chelation mode of 2-aminocyclopentene-1-dithiocarboxylic acid (acda) in its complexes with Ni(II), Pd(II) and Pt(II). The results strongly suggest that a (S,S) chelation models involved in this series of squa re-planar complexes. A previous assignment, based on infrared results only, is now extended, and the metal-sulfur stretching modes in the co mplexes are now assigned for the first time, on basis of the resonance Raman results. In the case of the Ni(II) complex, a selective enhance ment of distinctive chromophoric moieties was observed, suggesting the presence of two charge-transfer transitions not resolved under the br oad absorption band in the optical spectrum.